Why \b does not match word using .net regex

Question

To review regular expresions I read this tutorial. Anyways that tutorial mentions that `\b` matches a word boundary (between \w and \W characters). That tutorial also gives a link where you can install expresso (program that helps when creating regular expressions). So I have created my regular expressions in expresso and I do inded get a match. Now when I copy the same regex to visual studio I do not get a match. Take a look: Why am I not getting a match? in the immediate window I am showing the content of variable output. In expresso I do get a match and in visual studio I don't. why?

Accepted Answer

The C# language and .NET Regular Expressions both have their own distinct set of backslash-escape sequences, but the C# compiler is intercepting the `"\b"` in your string and converting it into an ASCII backspace character so the `RegEx` class never sees it. You need to make your string verbatim (prefix with an at-symbol) or double-escape the 'b' so the backslash is passed to RegEx like so:

```
@"\bCOMPILATION UNIT";
```

Or

```
"\bCOMPILATION UNIT"
```

I'll say the .NET RegEx documentation does not make this clear. It took me a while to figure this out at first too.

Fun-fact: The `` and `
` characters (carriage-return and line-break respectively) and some others are recognized by both RegEx and the C# language, so the end-result is the same, even if the compiled string is different.

Why \b does not match word using .net regex

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